Fig. 7: The proportion of otoferlin isoforms was altered under noise exposure and aging conditions.

a, b Maximum intensity z-projections of confocal sections of IHCs with double labeling for otoferlin isoforms from P30 wild-type whole-mount organ of Corti preparations (representative results of at least three biological replicates are shown). c Otof-C immunofluorescence density ratio (intensities were normalized against a dark background in the image and averaged per cell) in IHCs shows a significant discrepancy between the apical (about the 8 kHz region, n = 49), middle (about the 16 kHz region, n = 51), and basal turn (about the 32 kHz region, n = 66) from 8 mice. d The sustained exocytosis of IHCs was significantly higher in high-frequency regions than in low-frequency regions. e–g An episode of 2 h, 103 dB SPL, and 2–20 kHz bandpass noise exposure significantly elevated ABR thresholds within 24 h. The sustained exocytosis of synaptic vesicles was significantly reduced one day after noise exposure (f). The normalized Otof-C immunofluorescence density ratio in IHCs shows a significant discrepancy between pre-and post-noise exposure (a total of 92 and 77 cells of 8 mice from each group) (g). h–j Mice at 7 months old (P210) showed a significant elevation in ABR thresholds. The sustained exocytosis of synaptic vesicles was significantly reduced in aging mice (i). The normalized Otof-C immunofluorescence density ratio in IHCs showed a significant discrepancy between young and old mice (a total of 51 and 52 cells in 6 mice from each group) (j). Statistical analysis by one-way ANOVA followed by the Bonferroni post hoc test with significance indicated (c), two-way ANOVA followed by the Bonferroni post hoc test with significance indicated (e, h) and two-side unpaired t test or Mann-Whitney test with significance indicated (d, f, g, I, j). All data, statistical test used and p values can be found in the source data file.